1. Field of the Invention
This invention relates to an inductive element having a gap and a fabrication method thereof, and more particularly, to an inductive element that uses a linear spacer to control the size of the gap and a fabrication method thereof.
2. Description of Related Art
An inductive element is a passive element in an electronic circuit. An inductive element typically comprises a magnetic core and a coil. In electronic circuits, inductive element come in a variety of types depending on the desired attributes. One type of inductive element is an inductive element having a gap. Compared to an inductive element without a gap, an inductive element having a gap has a coil that is installed on a ferrite element to thereby provide lower inductance and greater current. The gap prevents the inductive element from entering the saturation state and becoming useless when current flows through the inductive element.
For a general inductive element having a gap, the larger the gap, the smaller the inductance of the inductive element becomes, and vice versa. Therefore, the inductive element may be manufactured to the desired inductance by controlling the size of the gap.
FIG. 1 is a perspective diagram of an inductive element 1 having a low inductance and high current-carrying capability according to the prior art. The inductive element 1 comprises an upper core body 11, a tape 12, an adhesive 14, a lower core body 15 and a coil 16. In fabrication, the adhesive 14 is covered on the lower core body 15, tape 12, which can endure high temperatures, is stuck to the upper core body 11, and then the upper core body 11 that is affixed with the tape 12 covers the lower core body 15 covered with the adhesive 14. The upper core body 11 is spaced apart from the lower core body 15 by the tape 12 of a predetermined thickness to form a gap, and is adhered to the lower core body 15 by the adhesive 14. In order for the upper core body 11 to be at a uniform distance from the lower core body 15 (i.e., the size of the gap), the tape 12 is fabricated to have a large surface area, and is applied to the contact surface between the upper core body 11 and the lower core body 15.
Therefore, such an inductive element 1 uses the tape 12 to establish the size of the gap, and the thicker the tape 12, the lower the inductance of the inductive element 1 becomes.
However, the inductive element of the prior art has the following drawbacks.
(1) The tape has too large an area in contact with the core bodies. As shown in FIG. 1, the large area occupied by the tape 12, which is used in order for the gap to have a uniform size, covers a significant portion of the side of the upper core body 11 that contacts the adhesive 14, such that the adhesive 14 cannot maximally adhere the upper core body 11 to the lower core body 15, leaving the upper core body 11 easily detachable from the lower core body 15.
(2) Use of the tape has low accuracy. As formerly stated, the inductance of the inductive element is affected by the gap size, and the gap of the inductive element has to have a uniform size. However, the tape used in the prior art has too large a tolerance (that is, the difference in the thickness of the tape at various places), so the inductive element does not have a uniform inductance.
(3) The inductive element of the prior art incurs high costs. There is a limited number of types of high-temperature endurable tapes in the market, so most users order their own dedicated tapes, which costs a lot of money, and the inductive element that uses such tapes have a correspondingly higher cost.
In conclusion, finding a way to provide an inductive element that can more accurately, securely and cheaply form the gap, and do so in a way that can tolerate the high temperatures encountered in manufacture or application, is an important goal in the art.